From: kasal@... (Stepan Kasal)
Date: 2002-07-11T17:30:36+09:00
Subject: Re: String#split converts string args to regexes -- ?

Hallo,

> Quick reminder, for reference :-)
> 
>   sub/gsub
> 
>    (a) prohibit string pattern
>    (b) string patterns as strings, without converting into regex.
> 
>   split
> 
>    (c) prohibit string pattern longer than 1.
>    (d) string patterns as strings, without converting into regex.

> On Wed, 10 Jul 2002, Stepan Kasal wrote:
> > So I vote for a-c, with an error message saying something like
> > "use either Regexp.new(s) or Regexp.new(Regexp.quote(s)) to clarify"

On Wed, 10 Jul 2002 12:35:54 GMT, David Alan Black wrote:
[...]
> It's partly a matter of documentation stating that String#split takes
> a string or a regex, without (anywhere I've seen) noting that the
> string has to be only one character long or else has to follow regex
> syntax (because it's really a regex).
> 
> I'm not sure what the disadvantage of allowing a string argument is.

The disadvantage is that people will often write "error[.]log", hoping
that this will match the string "error.log".  The reason for writing this
is not only the habit inherited from other languages, it may be simply
a program which used to work in a previous version of Ruby (though it
should not, according to the docs ;-).

How would you like if a review of a new version of Ruby said this:

	We experienced non-complete backward compatibility with this
	version, at least.  Our old programs just stopped working, though
	no error message appeared.  We traced this down to a
	(mis-)behaviour of the split() function.   [...]
	We recommend reviewing all your programs carefully before upgrading
	Ruby, especially in a production environment.

I know, similar reasoning applies to my solution (a-c with an error message),
at least to an extent, because the error is detected in runtime, so it may
last some time till the surprise appears.  But I think crashing programs
is better then changing the semantics of old programs in a weird way.

> It's not mandatory -- you can always use a regex (or even
> Regexp.new(s) :-)  -- so allowing strings (without auto-conversion to
> regex) doesn't take away any functionality.

I think that arguments like this one lead to non-elegant non-readable
languages.

Stepan